cpython/Lib/genericpath.py

"""
Path operations common to more than one OS
Do not use directly.  The OS specific modules import the appropriate
functions from this module themselves.
"""
import os
import stat

__all__ = ['commonprefix', 'exists', 'getatime', 'getctime', 'getmtime',
           'getsize', 'isdir', 'isfile']


# Does a path exist?
# This is false for dangling symbolic links on systems that support them.
def exists(path):
    """Test whether a path exists.  Returns False for broken symbolic links"""
    try:
        st = os.stat(path)
    except os.error:
        return False
    return True


# This follows symbolic links, so both islink() and isdir() can be true
# for the same path ono systems that support symlinks
def isfile(path):
    """Test whether a path is a regular file"""
    try:
        st = os.stat(path)
    except os.error:
        return False
    return stat.S_ISREG(st.st_mode)


# Is a path a directory?
# This follows symbolic links, so both islink() and isdir()
# can be true for the same path on systems that support symlinks
def isdir(s):
    """Return true if the pathname refers to an existing directory."""
    try:
        st = os.stat(s)
    except os.error:
        return False
    return stat.S_ISDIR(st.st_mode)


def getsize(filename):
    """Return the size of a file, reported by os.stat()."""
    return os.stat(filename).st_size


def getmtime(filename):
    """Return the last modification time of a file, reported by os.stat()."""
    return os.stat(filename).st_mtime


def getatime(filename):
    """Return the last access time of a file, reported by os.stat()."""
    return os.stat(filename).st_atime


def getctime(filename):
    """Return the metadata change time of a file, reported by os.stat()."""
    return os.stat(filename).st_ctime


# Return the longest prefix of all list elements.
def commonprefix(m):
    "Given a list of pathnames, returns the longest common leading component"
    if not m: return ''
    s1 = min(m)
    s2 = max(m)
    n = min(len(s1), len(s2))
    for i in xrange(n):
        if s1[i] != s2[i]:
            return s1[:i]
    return s1[:n]